From: Yan Zhao <yan.y.zhao@intel.com>
To: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: "Zhengxiao.zx@Alibaba-inc.com" <Zhengxiao.zx@alibaba-inc.com>,
"Tian, Kevin" <kevin.tian@intel.com>,
"Liu, Yi L" <yi.l.liu@intel.com>,
"cjia@nvidia.com" <cjia@nvidia.com>,
"eskultet@redhat.com" <eskultet@redhat.com>,
"Yang, Ziye" <ziye.yang@intel.com>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
"cohuck@redhat.com" <cohuck@redhat.com>,
"shuangtai.tst@alibaba-inc.com" <shuangtai.tst@alibaba-inc.com>,
"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
"Wang, Zhi A" <zhi.a.wang@intel.com>,
"mlevitsk@redhat.com" <mlevitsk@redhat.com>,
"pasic@linux.ibm.com" <pasic@linux.ibm.com>,
"aik@ozlabs.ru" <aik@ozlabs.ru>,
Kirti Wankhede <kwankhede@nvidia.com>,
"eauger@redhat.com" <eauger@redhat.com>,
"felipe@nutanix.com" <felipe@nutanix.com>,
"jonathan.davies@nutanix.com" <jonathan.davies@nutanix.com>,
"Liu, Changpeng" <changpeng.liu@intel.com>,
"Ken.Xue@amd.com" <Ken.Xue@amd.com>
Subject: Re: [Qemu-devel] [PATCH v7 00/13] Add migration support for VFIO device
Date: Thu, 11 Jul 2019 20:14:42 -0400 [thread overview]
Message-ID: <20190712001442.GD9176@joy-OptiPlex-7040> (raw)
In-Reply-To: <20190711162315.GP3971@work-vm>
On Fri, Jul 12, 2019 at 12:23:15AM +0800, Dr. David Alan Gilbert wrote:
> * Yan Zhao (yan.y.zhao@intel.com) wrote:
> > On Thu, Jul 11, 2019 at 06:50:12PM +0800, Dr. David Alan Gilbert wrote:
> > > * Yan Zhao (yan.y.zhao@intel.com) wrote:
> > > > Hi Kirti,
> > > > There are still unaddressed comments to your patches v4.
> > > > Would you mind addressing them?
> > > >
> > > > 1. should we register two migration interfaces simultaneously
> > > > (https://lists.gnu.org/archive/html/qemu-devel/2019-06/msg04750.html)
> > >
> > > Please don't do this.
> > > As far as I'm aware we currently only have one device that does that
> > > (vmxnet3) and a patch has just been posted that fixes/removes that.
> > >
> > > Dave
> > >
> > hi Dave,
> > Thanks for notifying this. but if we want to support postcopy in future,
> > after device stops, what interface could we use to transfer data of
> > device state only?
> > for postcopy, when source device stops, we need to transfer only
> > necessary device state to target vm before target vm starts, and we
> > don't want to transfer device memory as we'll do that after target vm
> > resuming.
>
> Hmm ok, lets see; that's got to happen in the call to:
> qemu_savevm_state_complete_precopy(fb, false, false);
> that's made from postcopy_start.
> (the false's are iterable_only and inactivate_disks)
>
> and at that time I believe the state is POSTCOPY_ACTIVE, so in_postcopy
> is true.
>
> If you're doing postcopy, then you'll probably define a has_postcopy()
> function, so qemu_savevm_state_complete_precopy will skip the
> save_live_complete_precopy call from it's loop for at least two of the
> reasons in it's big if.
>
> So you're right; you need the VMSD for this to happen in the second
> loop in qemu_savevm_state_complete_precopy. Hmm.
>
> Now, what worries me, and I don't know the answer, is how the section
> header for the vmstate and the section header for an iteration look
> on the stream; how are they different?
>
may we name one "vfio" and the other "vfio-vmsd", and let iteration
interface for device memory data and vmstate interface for device state
data?
Thanks
Yan
> Dave
>
> > Thanks
> > Yan
> >
> > > > 2. in each save iteration, how much data is to be saved
> > > > (https://lists.gnu.org/archive/html/qemu-devel/2019-06/msg04683.html)
> > > > 3. do we need extra interface to get data for device state only
> > > > (https://lists.gnu.org/archive/html/qemu-devel/2019-06/msg04812.html)
> > > > 4. definition of dirty page copied_pfn
> > > > (https://lists.gnu.org/archive/html/qemu-devel/2019-06/msg05592.html)
> > > >
> > > > Also, I'm glad to see that you updated code by following my comments below,
> > > > but please don't forget to reply my comments next time:)
> > > > https://lists.gnu.org/archive/html/qemu-devel/2019-06/msg05357.html
> > > > https://lists.gnu.org/archive/html/qemu-devel/2019-06/msg06454.html
> > > >
> > > > Thanks
> > > > Yan
> > > >
> > > > On Tue, Jul 09, 2019 at 05:49:07PM +0800, Kirti Wankhede wrote:
> > > > > Add migration support for VFIO device
> > > > >
> > > > > This Patch set include patches as below:
> > > > > - Define KABI for VFIO device for migration support.
> > > > > - Added save and restore functions for PCI configuration space
> > > > > - Generic migration functionality for VFIO device.
> > > > > * This patch set adds functionality only for PCI devices, but can be
> > > > > extended to other VFIO devices.
> > > > > * Added all the basic functions required for pre-copy, stop-and-copy and
> > > > > resume phases of migration.
> > > > > * Added state change notifier and from that notifier function, VFIO
> > > > > device's state changed is conveyed to VFIO device driver.
> > > > > * During save setup phase and resume/load setup phase, migration region
> > > > > is queried and is used to read/write VFIO device data.
> > > > > * .save_live_pending and .save_live_iterate are implemented to use QEMU's
> > > > > functionality of iteration during pre-copy phase.
> > > > > * In .save_live_complete_precopy, that is in stop-and-copy phase,
> > > > > iteration to read data from VFIO device driver is implemented till pending
> > > > > bytes returned by driver are not zero.
> > > > > * Added function to get dirty pages bitmap for the pages which are used by
> > > > > driver.
> > > > > - Add vfio_listerner_log_sync to mark dirty pages.
> > > > > - Make VFIO PCI device migration capable. If migration region is not provided by
> > > > > driver, migration is blocked.
> > > > >
> > > > > Below is the flow of state change for live migration where states in brackets
> > > > > represent VM state, migration state and VFIO device state as:
> > > > > (VM state, MIGRATION_STATUS, VFIO_DEVICE_STATE)
> > > > >
> > > > > Live migration save path:
> > > > > QEMU normal running state
> > > > > (RUNNING, _NONE, _RUNNING)
> > > > > |
> > > > > migrate_init spawns migration_thread.
> > > > > (RUNNING, _SETUP, _RUNNING|_SAVING)
> > > > > Migration thread then calls each device's .save_setup()
> > > > > |
> > > > > (RUNNING, _ACTIVE, _RUNNING|_SAVING)
> > > > > If device is active, get pending bytes by .save_live_pending()
> > > > > if pending bytes >= threshold_size, call save_live_iterate()
> > > > > Data of VFIO device for pre-copy phase is copied.
> > > > > Iterate till pending bytes converge and are less than threshold
> > > > > |
> > > > > On migration completion, vCPUs stops and calls .save_live_complete_precopy
> > > > > for each active device. VFIO device is then transitioned in
> > > > > _SAVING state.
> > > > > (FINISH_MIGRATE, _DEVICE, _SAVING)
> > > > > For VFIO device, iterate in .save_live_complete_precopy until
> > > > > pending data is 0.
> > > > > (FINISH_MIGRATE, _DEVICE, _STOPPED)
> > > > > |
> > > > > (FINISH_MIGRATE, _COMPLETED, STOPPED)
> > > > > Migraton thread schedule cleanup bottom half and exit
> > > > >
> > > > > Live migration resume path:
> > > > > Incomming migration calls .load_setup for each device
> > > > > (RESTORE_VM, _ACTIVE, STOPPED)
> > > > > |
> > > > > For each device, .load_state is called for that device section data
> > > > > |
> > > > > At the end, called .load_cleanup for each device and vCPUs are started.
> > > > > |
> > > > > (RUNNING, _NONE, _RUNNING)
> > > > >
> > > > > Note that:
> > > > > - Migration post copy is not supported.
> > > > >
> > > > > v6 -> v7:
> > > > > - Fix build failures.
> > > > >
> > > > > v5 -> v6:
> > > > > - Fix build failure.
> > > > >
> > > > > v4 -> v5:
> > > > > - Added decriptive comment about the sequence of access of members of structure
> > > > > vfio_device_migration_info to be followed based on Alex's suggestion
> > > > > - Updated get dirty pages sequence.
> > > > > - As per Cornelia Huck's suggestion, added callbacks to VFIODeviceOps to
> > > > > get_object, save_config and load_config.
> > > > > - Fixed multiple nit picks.
> > > > > - Tested live migration with multiple vfio device assigned to a VM.
> > > > >
> > > > > v3 -> v4:
> > > > > - Added one more bit for _RESUMING flag to be set explicitly.
> > > > > - data_offset field is read-only for user space application.
> > > > > - data_size is read for every iteration before reading data from migration, that
> > > > > is removed assumption that data will be till end of migration region.
> > > > > - If vendor driver supports mappable sparsed region, map those region during
> > > > > setup state of save/load, similarly unmap those from cleanup routines.
> > > > > - Handles race condition that causes data corruption in migration region during
> > > > > save device state by adding mutex and serialiaing save_buffer and
> > > > > get_dirty_pages routines.
> > > > > - Skip called get_dirty_pages routine for mapped MMIO region of device.
> > > > > - Added trace events.
> > > > > - Splitted into multiple functional patches.
> > > > >
> > > > > v2 -> v3:
> > > > > - Removed enum of VFIO device states. Defined VFIO device state with 2 bits.
> > > > > - Re-structured vfio_device_migration_info to keep it minimal and defined action
> > > > > on read and write access on its members.
> > > > >
> > > > > v1 -> v2:
> > > > > - Defined MIGRATION region type and sub-type which should be used with region
> > > > > type capability.
> > > > > - Re-structured vfio_device_migration_info. This structure will be placed at 0th
> > > > > offset of migration region.
> > > > > - Replaced ioctl with read/write for trapped part of migration region.
> > > > > - Added both type of access support, trapped or mmapped, for data section of the
> > > > > region.
> > > > > - Moved PCI device functions to pci file.
> > > > > - Added iteration to get dirty page bitmap until bitmap for all requested pages
> > > > > are copied.
> > > > >
> > > > > Thanks,
> > > > > Kirti
> > > > >
> > > > > Kirti Wankhede (13):
> > > > > vfio: KABI for migration interface
> > > > > vfio: Add function to unmap VFIO region
> > > > > vfio: Add vfio_get_object callback to VFIODeviceOps
> > > > > vfio: Add save and load functions for VFIO PCI devices
> > > > > vfio: Add migration region initialization and finalize function
> > > > > vfio: Add VM state change handler to know state of VM
> > > > > vfio: Add migration state change notifier
> > > > > vfio: Register SaveVMHandlers for VFIO device
> > > > > vfio: Add save state functions to SaveVMHandlers
> > > > > vfio: Add load state functions to SaveVMHandlers
> > > > > vfio: Add function to get dirty page list
> > > > > vfio: Add vfio_listerner_log_sync to mark dirty pages
> > > > > vfio: Make vfio-pci device migration capable.
> > > > >
> > > > > hw/vfio/Makefile.objs | 2 +-
> > > > > hw/vfio/common.c | 55 +++
> > > > > hw/vfio/migration.c | 874 ++++++++++++++++++++++++++++++++++++++++++
> > > > > hw/vfio/pci.c | 137 ++++++-
> > > > > hw/vfio/trace-events | 19 +
> > > > > include/hw/vfio/vfio-common.h | 25 ++
> > > > > linux-headers/linux/vfio.h | 166 ++++++++
> > > > > 7 files changed, 1271 insertions(+), 7 deletions(-)
> > > > > create mode 100644 hw/vfio/migration.c
> > > > >
> > > > > --
> > > > > 2.7.0
> > > > >
> > > --
> > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
prev parent reply other threads:[~2019-07-12 0:21 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-09 9:49 [Qemu-devel] [PATCH v7 00/13] Add migration support for VFIO device Kirti Wankhede
2019-07-09 9:49 ` [Qemu-devel] [PATCH v7 01/13] vfio: KABI for migration interface Kirti Wankhede
2019-07-16 20:56 ` Alex Williamson
2019-07-17 11:55 ` Cornelia Huck
2019-07-23 12:13 ` Cornelia Huck
2019-08-21 20:32 ` Kirti Wankhede
2019-08-21 20:31 ` Kirti Wankhede
2019-07-09 9:49 ` [Qemu-devel] [PATCH v7 02/13] vfio: Add function to unmap VFIO region Kirti Wankhede
2019-07-16 16:29 ` Cornelia Huck
2019-07-18 18:54 ` Kirti Wankhede
2019-07-09 9:49 ` [Qemu-devel] [PATCH v7 03/13] vfio: Add vfio_get_object callback to VFIODeviceOps Kirti Wankhede
2019-07-16 16:32 ` Cornelia Huck
2019-07-09 9:49 ` [Qemu-devel] [PATCH v7 04/13] vfio: Add save and load functions for VFIO PCI devices Kirti Wankhede
2019-07-11 12:07 ` Dr. David Alan Gilbert
2019-08-22 4:50 ` Kirti Wankhede
2019-08-22 9:32 ` Dr. David Alan Gilbert
2019-08-22 19:10 ` Kirti Wankhede
2019-08-22 19:13 ` Dr. David Alan Gilbert
2019-08-22 23:57 ` Tian, Kevin
2019-08-23 9:26 ` Dr. David Alan Gilbert
2019-08-23 9:49 ` Tian, Kevin
2019-07-16 21:14 ` Alex Williamson
2019-07-17 9:10 ` Dr. David Alan Gilbert
2019-07-09 9:49 ` [Qemu-devel] [PATCH v7 05/13] vfio: Add migration region initialization and finalize function Kirti Wankhede
2019-07-16 21:37 ` Alex Williamson
2019-07-18 20:19 ` Kirti Wankhede
2019-07-23 12:52 ` Cornelia Huck
2019-07-09 9:49 ` [Qemu-devel] [PATCH v7 06/13] vfio: Add VM state change handler to know state of VM Kirti Wankhede
2019-07-11 12:13 ` Dr. David Alan Gilbert
2019-07-11 19:14 ` Kirti Wankhede
2019-07-22 8:23 ` Yan Zhao
2019-08-20 20:31 ` Kirti Wankhede
2019-07-16 22:03 ` Alex Williamson
2019-07-22 8:37 ` Yan Zhao
2019-08-20 20:33 ` Kirti Wankhede
2019-08-23 1:32 ` Yan Zhao
2019-07-09 9:49 ` [Qemu-devel] [PATCH v7 07/13] vfio: Add migration state change notifier Kirti Wankhede
2019-07-17 2:25 ` Yan Zhao
2019-08-20 20:24 ` Kirti Wankhede
2019-08-23 0:54 ` Yan Zhao
2019-07-09 9:49 ` [Qemu-devel] [PATCH v7 08/13] vfio: Register SaveVMHandlers for VFIO device Kirti Wankhede
2019-07-22 8:34 ` Yan Zhao
2019-08-20 20:33 ` Kirti Wankhede
2019-08-23 1:23 ` Yan Zhao
2019-07-09 9:49 ` [Qemu-devel] [PATCH v7 09/13] vfio: Add save state functions to SaveVMHandlers Kirti Wankhede
2019-07-12 2:44 ` Yan Zhao
2019-07-18 18:45 ` Kirti Wankhede
2019-07-17 2:50 ` Yan Zhao
2019-08-20 20:30 ` Kirti Wankhede
2019-07-09 9:49 ` [Qemu-devel] [PATCH v7 10/13] vfio: Add load " Kirti Wankhede
2019-07-12 2:52 ` Yan Zhao
2019-07-18 19:00 ` Kirti Wankhede
2019-07-22 3:20 ` Yan Zhao
2019-07-22 19:07 ` Alex Williamson
2019-07-22 21:50 ` Yan Zhao
2019-08-20 20:35 ` Kirti Wankhede
2019-07-09 9:49 ` [Qemu-devel] [PATCH v7 11/13] vfio: Add function to get dirty page list Kirti Wankhede
2019-07-12 0:33 ` Yan Zhao
2019-07-18 18:39 ` Kirti Wankhede
2019-07-19 1:24 ` Yan Zhao
2019-07-22 8:39 ` Yan Zhao
2019-08-20 20:34 ` Kirti Wankhede
2019-07-09 9:49 ` [Qemu-devel] [PATCH v7 12/13] vfio: Add vfio_listerner_log_sync to mark dirty pages Kirti Wankhede
2019-07-23 13:18 ` Cornelia Huck
2019-07-09 9:49 ` [Qemu-devel] [PATCH v7 13/13] vfio: Make vfio-pci device migration capable Kirti Wankhede
2019-07-11 2:55 ` [Qemu-devel] [PATCH v7 00/13] Add migration support for VFIO device Yan Zhao
2019-07-11 10:50 ` Dr. David Alan Gilbert
2019-07-11 11:47 ` Yan Zhao
2019-07-11 16:23 ` Dr. David Alan Gilbert
2019-07-11 19:08 ` Kirti Wankhede
2019-07-12 0:32 ` Yan Zhao
2019-07-18 18:32 ` Kirti Wankhede
2019-07-19 1:23 ` Yan Zhao
2019-07-24 11:32 ` Dr. David Alan Gilbert
2019-07-12 17:42 ` Dr. David Alan Gilbert
2019-07-15 0:35 ` Yan Zhao
2019-07-12 0:14 ` Yan Zhao [this message]
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